Design Proposal
Research Topic: Cavity Depth Variation in Building Envelopes
Background:
The building envelope can have a significant impact on the thermal environment of an interior space, influencing the rate at which a space reaches its ideal thermal comfort temperature. Thermal comfort is the outcome of a well-balanced combination of building systems adapted to the building's location and program. In the physical environment, thermal energy is transferred through conduction, radiation and convection. A balanced thermal environment is essential to feeling comfortable within a building. A person’s concentration, level of fatigue and manual and mental dexterity are all influenced by excessively high or low temperatures. Key considerations for designing for thermal comfort include air tightness and ventilation, thermal inertia, solar gain and insulation of the building envelope.
Research Question:
How does the cavity depth of a building envelope impact the passive heat transfer to an enclosed interior space? How does this method of convection influence the amount of time an interior space takes to reach its ideal thermal comfort temperature?
Hypothesis:
A building envelope with a smaller cavity depth will help an interior space reach its ideal thermal comfort temperature in the shortest amount of time.
Abstract:
In order to achieve ideal thermal comfort temperatures within an interior space, a well-balanced combination of building systems needs to be adapted and optimized to fit the building’s needs, based upon its location and its program. Through the observation of multi-layer building envelopes, we intended to test how heated air passed through the building envelope in order to passively heat an interior space. The primary test consisted of a glass water tank with two chambers, one containing cold water and the other containing boiling water, separated by a cavity formed by interchangeable acrylic sheets. This cavity contained room temperature water. The acrylic sheet layers included a perforated sheet and a solid sheet. The perforated sheet was used to allow water to pass into the center cavity, representing heated air moving into the building envelope. A separate test included two solid acrylic sheet layers, in which we monitored the central cavity to observe how the building envelope performs between hot and cold temperatures. Through the tests, the depth of the central cavity was widened to measure how heat transfer was effected as the cavity gets wider. The two tests worked to convey the efficiency of a building envelope and how the depth of the cavity between each chamber influenced the heat transfer from one chamber to the other.
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Material Inventory & Budget:
Prototype:
1/16" Acrylic Sheet-$8
1/8" Acrylic Sheet- $8
Applicator Bottle -$5
Painter's Tape-$10
Weld-on Acrylic Bonding-$19.50
Aquarium Silicone-$6.50
Total: $57
Mock-up & Final:
5.5 Gallon Fish Tank-$17
1/8" Acrylic Sheet - $8
Black Ink - $8
Total: $33
1/16" Acrylic Sheet-$8
1/8" Acrylic Sheet- $8
Applicator Bottle -$5
Painter's Tape-$10
Weld-on Acrylic Bonding-$19.50
Aquarium Silicone-$6.50
Total: $57
Mock-up & Final:
5.5 Gallon Fish Tank-$17
1/8" Acrylic Sheet - $8
Black Ink - $8
Total: $33
Schedule:
Fabrication Strategy:
A glass water tank with two chambers, one containing cold water and the other containing boiling water, separated by a cavity formed by interchangeable acrylic sheets. This cavity contained room temperature water. The two types of building envelopes being tested: Type A which is two solid acrylic sheets and Type B consisting of a solid and a perforated acrylic sheet. Type A is exploring the effectiveness of a building envelope/cavity and how that affects the heat transfer to an enclosed interior space. Type B explores how effective heating an interior space is by allowing the hot water to travel into the cavity and capturing it to passively heat the other chamber. The acrylic sheets are spaced: 2",4", and 6" apart from the 6” interior chamber and sit within a channel created by two acrylic strips. An LCD screen, Arduino, and breadboard sit inside a 3D printed sleeve that hangs over the edge of the box with the temperature probes (DS18B20) attached and placed inside the interior chamber with the cold water. During the test of Type A, ink is dropped into the cavity to create a visual of how the two extreme temperatures affect the inside of the cavity while the temperature of the interior chamber is monitored by the DS18B20. During the Type B tests ink is dropped into the hot water to show how the hot water is moving through the perforated sheet into the cavity while the time and temperature of the interior chamber are being monitored.
Digital Fabrication:
Laser Cutter- Acrylic Pieces
3D Printer- Slot to hold acrylic sheets and Arduino Holder
Laser Cutter- Acrylic Pieces
3D Printer- Slot to hold acrylic sheets and Arduino Holder
Controls (Electronics)
For all of our testing, we used a DS18B20 Temperature Sensor paired with Arduino UNO to measure and document the temperatures of the interior chamber. An 16"x2" LCD display recorded the temperature during both tests when water is added to the chambers specifically when the heated water passes into the cavity of the envelope.
